Chronograph



oct. 12,` 1954 s, STANDAL 2,691,415

CHRONOGRAPH Filed May 19, 1952 3 Sheets-r-Sheet l u n Q?, Ik@

@l i A kb G , /W-Q \O\/y/// I INVENTOR. Jian/ey .jandol BY Oct. l2, 1954 s. sTANDAL 2,691,415

CHRONOGRAPH Filed May 19, 1952 3 Sheets-Sheet 2 fr i- L f g# 5f j. 4

45k if 57 55 4 l z 47 9 l C 49 4a IN V EN T 0R.

Smal@ @www BMJ@ Oct. l2, 1954 s. s'rANDAl. 2,691,415

CHRNOGRAPH Filed May 19, 1952 3 Sheets-Sheet 3 -INVENTOK Stanley Stena/QZ Patented Oct. 12, 1954 UNITED STATES OFFICE 6 Claims. l

My invention relates to improvements in devices for determining the velocity of projectiles red 'from rearms by measuring the time of travel of the projectile from a point close to the muzzle of the rearm over a measured distance. Instruments of this general nature are referred to among those engaged in determining projectile velocities as clironographs. Hereafter in the description and claims the word chronograph shall be used to designate the instrument. In the measurement of projectile velocity by this method, the velocity obtained is not the muzzle velocity. It is instead a mean velocity of the projectile over the measured distance. If the distance is reasonably short and the measurement is taken from close to the muzzle of the firearm, the mean velocity obtained in this way is a close approach to the actual muzzle velocity. It is always lower than the actual muzzle velocity.

It is the principal purpose of my invention to provide a device of the nature above referred to which is simple in construction so that it may be made available at a reasonably low cost to all those interested in measuring the velocity of projectiles fired from their rearms with varying loads. Speciiically my invention contemplates the provision of a chronograph which embodies a suspended rod that can be severed from its suspension strand by the ired projectile, in combination with a target located at the measured distance from the suspended rod, a marking means for marking the rod while it is suspended and while it is falling, the marking means being actuated by breaking an electrical circuit when the target is struck by the projectile. The chronograph embodying these features provides a reading on the falling rod which can be measured. From this reading the time of travel of the projectile from the severed strand to the target can be calculated. With this information it is an easy matter to establish the average or mid range velocity of the projectile over the measured distance, and charts may be made to convert the readings on the rod directly into velocity in feet per second.

The more detailed objects and advantages of my invention will appear from the following description and the accompanying drawings in which a preferred form of the invention is shown. It should be understood, however, that the drawings and description are illustrative only and are not intended to limit the invention except insofar as it is limited by the claims.

In the drawings:

Figure 1 is a somewhat diagrammatic view of 55 a completed chronograph embodying my invention;

Figure 2 is an enlarged view in side elevation looking at Figure 1 from the line 2-2;

Figure 3 is a sectional view taken on the line 3-3 of Figure 2;

Figure 4 is a plan View looking down on the construction shown in Figure 2;

Figure 5 is an enlarged view in side elevation looking at Figure 1 substantially from the line 5 5;

Figure 6 is an enlarged fragmentary sectional view taken on the line 6--5 of Figure 5;

Figure 7 is an enlarged sectional View taken on the line l-'I of Figure 5; and

Figure 8 is a sectional view on the line 8-8 of Figure 7.

Referring now in detail to the drawings, my improved chronograph employs as its principal indicating device a suspended rod ID, in a support Il which is in the form of a shell. The term rod is used herein in its broad sense. The member Ill may be of any material. It may be hollow and its shape in cross section may be varied. It needs to be of substantial length and of such construction that it will fall relatively straight when released from a suspension member that is secured to it at the top. The support Il has a base I2 which may be leveled on a supporting member I3 by means of three leveling screws I4 that are threaded into the base I2 and spaced apart about the support II.

The rod I il has means at its upper end to attach a supporting strand I5. As shown, the strand I5 is a narrow tape and the means for securing it to the rod IU comprises a slot I6 in the upper end of the rod and a screw I'I threaded into the rod to secure the strand I5 in the slot I5. The strand I5 is suspended from a hanger rod I8 which is carried by a vertically adjustable support I9. The hanger rod I8 extends up through the support and is resiliently suspended, to maintain tension on the strand I5, by providing a spring 2U between a top cap 2l and a stop 22 on the support It. The cap 2l is threaded on the upper end of the hanger rod I8. The support I9 has a bar 23 that extends down through a sleeve 2d on the supporting shield II. A set screw 25 is used to hold the bar 23 at the desired vertical level in the sleeve 24.

As shown best in Figure l, the strand I5 is positioned to be cut by a projectile P red from the muzzle M of a rie or other firearm. When the strand I5 is cut by the projectile, the rod IE) is free to fall. It will be appreciated that the force of the explosion from the rifle driving the projectile forward will exert a lateral force on the strand which will be communicated to the rod unless some means are provided to prevent it. This lateral force will deflect the rod laterally at the top. I provide guide means 25 above the rod and below that portion of the strand I which is to be severed by the projectile. This guide means acts on the strand I5 to keep it from communicating lateral force to the rod I0. It also cooperates with the spring 29 to keep the strand from jerking the rod upward, The guide means 26 comprises a yoke, the top portion 21 of which, extends across the top of the support I I. A shallow curved recess 28 is formed in one edge of the portion 21 and at the base of this recess, there is a narrow7 slot 29 to receive the strand I5. The member 21 is also cut away at 30 around the slot 29 so as to avoid any dragging or retarding eiect on the strand after it is severed. The legs 3I and 32 of the member 26` are pivoted to the upper end of the support shield II by screws 33 and 34. A wing head set screw 35 locks the member 26 in position but permits it to be turned aside whenever the rod is being attached to a new support strand I5.

At least a substantial portion of the rod I9 is provided with a markable coating indicated at 36 in Figure 6. This markable coating need not cover the entire rod but it must cover that portion of the rod which is directed toward an opening IIa in the support shield II so that a chisel 31 can be brought into contact with the coating through the opening IIa in order to mark the coating.

The chisel 31 is carried by the core 38 of an electromagnet 39 which is mounted on a bracket 46. The bracket 40 is secured to the support II at the base of the opening I Ia. The electromagnet 39 is adapted to hold the core 38 and the chisel 31 retracted out of engagement with the rod IIJ. It also provides a guide for the chisel to guide it toward the rod I0. A spring 4i is mounted within the electromagnet 39 to propel the chisel forward against the rod whenever current is cut off from the coil 42 of the electromagnet. An adjustable head 43 is threaded into the cap 44 of the electromagnet and provides a stop limiting the advance movement of the chisel. The head 43 also provides a guide bearing for the chisel 31.

The chronograph further includes a target 45 which is to be engaged by the projectile P, after the projectile travels a measured distance from the strand I5. The target 45 is pivotally suspended on a support 46 in the manner shown best by Figures 2, 3 and 4. A clamp 41 is adapted to engage the support 46 and be secured thereto by a wing head set screw 48. rlhe clamp 41 has an inverted channel shaped bracket 45 welded thereto. It also has a rearwardly extending arm 50 welded thereto. The target 45 has its upper edge curled around as shown at 5I in Figures 2 and 3 to provide a pivotal mounting of the target on a bolt 52 that extends through the legs of the bracket 49. The target 45 is a sheet of metal which has a bent up portion 45a back of the target face and positioned to engage a back stop pin 53, when the target is hit by a projectile and swung back. The stop pin 53 is secured to the arm 50.

A circuit breaker 54 is attached to the target 45. One conductor 55 is secured to the target sheet 45 by a terminal screw 56. Another conductor 51 is secured to a contact pin 58 that is mounted in a block 59 of insulation which is xed to the bracket 49. It is obvious that if the target 45 is swung to the left as shown in Figure 3, the finger 54 will break the circuit between the contact pin 58 and the target plate 45 which is connected to the conductor 55. The conductor 55 leads to one terminal 60 of a battery 6 I. The conductor 51 leads to one terminal 42a of the electromagnet coil 42. The other terminal 42h of the electromagnet coil 42 is connected to a conductor 62 which leads to the other terminal 63 of the battery 6I. With this construction the souce of current, the battery 6I, has the circuit breaker finger 54, the contact pin 58 and the electromagnet coil connected in series across it. If the projectile strikes the target 45 and separates the circuit breaker 54 from the contact pin 58, the coil 42 of the electromagnet is deenergized so that the spring 4I can drive the chisel 31 forward to contact the rod I0.

It is believed that the construction of the chronograph will be clear from the foregoing description. It is operated in a manner which will now be described.

Each instrument, when set up for operation, needs to be tested for lag. The lag is the delay inherent in the mechanism from the time the circuit is broken for the electromagnet until the chisel strikes the rod. The base I2 is mounted on a bench, table or box I3 which may desirably be provided with an aperture I3a so that the falling rod I0 will have room to drop the necessary amount for indexing. If the supporting shell II is long enough from the chisel down, this opening is not necessary. Preferably the shell II is lined with a soft material to avoid scarring or marking the rod I0. The rod I9 is attached to the strand I5 and lowered into the shell I I, the guide 26 being swung out of the way. The upper end of the tape is then fastened to the tape hanger rod I8 and the guide 26 is swung back into place so that the tape I5 enters the slot 29. The guide 26 is then locked in place and the bar 23 is raised until the rod I2 is at the proper height, that is, just in contact with the under face of the guide 26. The spring 2!) is compressed enough to apply about two pounds tension on the tape I5. This is enough to hold the rod III in contact with the guide 26, in case the tape stretches due to atmospheric changes or other reasons. The next step is to mark the rod with the chisel. The rod is simply swung forward gently until it contacts the chisel and is then moved laterally a small amount so that the point of the chisel will form a visible mar-k in the coating 36 on the rod.

In order to test for lag, the target 45 is brought forward so as to be approximately an inch away from the tape I5. The chisel is then retracted and the leads 55 and 62 are connected to the battery 6I so as to energize the electromagnet 39 under control of the target circuit breaker 54. The gun is then fired to cut the strand I5 and of course, the projectile will swing the target 45 back so as to break the circuit at the finger 54. This will allow the spring 4I to move the chisel forward to strike the rod I0 and form a mark in the coating 46. The distance between the original mark made in the coating 36 and this mark is the maximum of the lag, or the time delay from the breaking of the circuit at 54 until the chisel 31 hits the rod. This distance which is very small, is deducted from the subsequent rod measurements made when testing for velocity. In actual testing the equipment is set up in the same manner as testing for lag, except that the target 45 is placed a substantial distance away from the tape I5. For low velocity shooting a distance of about 100 feet between the target 45 and the tape i5' is adequate. For high velocity 'shooting the distance should be greater; A distance of v150 feet has been found to give accurate results.

This instrument provides a simple reliable device for obtaining a close approximation of the muzzle velocity of a charge fired from any rearm.` It does not include any costly or complicated electrical system. If the measurement between `marks on the rod Ill is made accurately the actual average velocity` of the projectile over the measured distance is readily obtained. The provision of the guide 26 prevents movement of the rod I laterally or upwardly due to the impact of the projectile on the strand l5. The only'replacements necessary comprise a fresh strand I for each ring and occasional replacement of the target i5 when it becomes damaged by the projectiles. The amount of current drain on the battery 6I can be kept down by disconnecting the battery except during the time necessary to perform each ring test. The electromagnet 39 does not need to be strong. All it has to do is hold the chisel retracted. If the rod does strike the chisel again while falling after the rlrst mark is made, no harm is done because the measurement is made from the starting mark to the lowest mark made while the rod is falling.

It is believed that the nature and advantages of my invention Will be clear from the foregoing description. Having described my invention, I claim:

1. A chronograph for determining velocity of projectiles iired from firearms by timing their flight over a measured distance comprising, a rod coated along one face for a part of its length with a markable coating, a severable suspension strand attached to the rod, a support for the rod, means at the top of the support for mounting said strand so that the rod hangs free and a portion of the suspension strand above the rod is exposed for severance by the projectile, a chisel mounted at the side or" the support to point toward and strike the markable coating on the rod, an electromagnet holding the chisel spaced from the rod, a spring urging the chisel toward the rod, a target member positioned at a measured distance from the suspension strand, a source of current, a circuit breaker attached to the target and wiring connections connecting the electromamgnet, the source of current and the circuit breaker in series.

2. A chronograph for determining velocity of projectiles fired from rearms by timing their night over a measured distance comprising, a rod coated along one face for a part of its length with a markable coating, a severable suspension strand attached to the rod, a support for the rod, means at the top of the support for mounting said strand so that the rod hangs free and a portion of the suspension strand above the rod is exposed for severance by the projectile, means on the support below said portion of the strand preventing lateral movement of the rod by the lateral force of the projectile against said portion, a chisel mounted at the side of the support to point toward and strike the markable coating on the rod, an electromagnet holding the chisel spaced from the rod, a spring urging the chisel toward the rod, a target member posi* tioned at a measured distance from the suspension strand, a source of current, a circuit breaker attached to the target and wiring connections connecting the electromagnet, the source of current and the circuit breaker in series.

6 'f3'. A chronograph for determining velocity of projectiles firedfrom nrearms by timing `their flight over a measured distance comprising, a rod coated along one face for a part of its length with a markable coating, a severable suspension strand attached to the rod,a support for the rod, including a shell surrounding the rod and having 'an opening in its side through which the coating is exposed, means at the top ofthe support for mounting said strand so that the rod hangs `free and a portion of the suspension strand above the rod is exposed for severance by the projectile, means on the support below said portion of the strand preventing lateral movement of the rod by the lateral force of the projectile against said portion, a chisel mounted at the side of the support at said opening to point toward and strike the markable coating on the rod, an electromagnet holding the chisel spaced from the rod, a spring urging the chisel toward the rod, a target member positioned at a measured distance from the suspension strand,

a source of current, a circuit breaker attached to the target and wiring connections connecting the electromagnet, the source of current and the circuit breaker in series.

4. A chronograph for determining velocity of projectiles red from firearms by timing their flight over a measured distance comprising, a rod coated along one face for a part of its length with a markable coating, a severable suspension strand attached to the rod, a support for the rod, including a shell surrounding the rod below said portion of the strand and having an opening in its side through which the coating is exposed, means at the top of the support for mounting said strand so that the rod hangs free and a portion of the suspension strand above the rod is exposed for severance by the projectile, a chisel mounted at the side of the support of said opening to point toward and strike the markable coating on the rod, an electromagnet holding the chisel spaced from the rod, a spring urging the chisel toward the rod, a target member positioned at a measured distance from the suspension strand, a source of current, a circuit breaker attached to the target and wiring connections connecting the electromagnet, the source of current and the circuit breaker in series.

5. A chronograph for determining velocity of projectiles red from firearms by timing their ight over a measured distance comprising, a rod coated along one face for a part of its length with a markable coating, a severable suspension strand attached to the rod, a support for the rod, means at the top of the support for mounting said strand so that the rod hangs free and a portion of the suspension strand above the rod is exposed for severance by the projectile, a chisel mounted at the side of the support to point toward and strike the markable coating on the rod, an electromagnet holding the chisel spaced from the rod, a spring urging the chisel toward the rod, a target member positioned at a measured distance from the suspension strand, a support from which the target is pivotally suspended, a backstop for the target carried by the support, a source of current, a circuit breaker attached to the target and wiring connections connecting the electromagnet, the source of current and the circuit breaker in series.

6. In a chronograph of the character described, a rod coated along one face for a part of its length with a markable coating, a severable suspension strand attached to the rod, a shell surrounding the rod and having an opening in its side through which the coating is exposed, a chisel mounted at the side of the shell at said opening to point toward and strike the markable coating on the rod, a target member positioned at a measured distance from said strand, means operable by movement of said target to drive the chisel against the rod, a yieldable support for said strand mounted on said shell, and a. strand guide on the shell having a slot therein through which the strand passes, said guide providing a. stop for the rod, and the yieldable support holding the rod against said guide.

References Cited in the file of this patent 

